Schematic chemical structure of the circumstellar shell of an AGB star |
圖片來源: Kemper, Francisca
The top half of the plot represents the chemistry in an
oxygen-rich environment (C/O < 1), and the bottom half of the figure
shows the carbon-rich counterpart.
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The logarithmic scale at the bottom
shows the distance and temperature to the center of the star. Several
distinct zones can be identified, namely the molecular formation
region and the dust formation region, where conditions are governed by
the density and the stellar radiation field, and the outermost region
where the chemistry is dominated by the impinging interstellar
radiation. |